In recent years, liquid crystal display devices are widely used as a display device of smartphones, tablet computers, vehicle-navigation systems, etc. In general, a liquid crystal display device comprises a liquid crystal display panel and a backlight device overlaid on the rear surface of the liquid crystal display panel and illuminates the liquid crystal display panel. The backlight device includes a reflective layer, a light guide, an optical sheet, a light source unit which irradiates light which enters the light guide, and also a case (bezel) made from a metal plate, which accommodates these members. The light source unit includes a wiring board and a plurality of light sources, for example, light-emitting diodes (LEDs) mounted on the wiring board. Meanwhile, such a backlight device is provided, that includes a mold frame provided in the case.
In recent years, as display areas have increased, there has been a continually constant demand for the frames of liquid crystal display devices to become ever narrower and the liquid crystal display devices to become ever thinner. However, the dimensions such as width, thickness, etc., of the frame in the above-described backlight device is approaching the structural limit, and such a demand of further thinning and narrowing the frame is difficult to achieve.